Portable power hammer



J1me 1935' J. H. BLAKE 2,006,065

PORTABLE POWER HAMMER Filed Jan. 27, 1934 INVENTOR 2 .5%); m Blake 5- zrfi Patented June 25, 1935 UNITED STATES PATENT oFFlcE 2,006,065FORTABLE POWER HAMMER Joseph H. Blake, Seattle, Wash.

Application January 2'7, 1934, Serial No. 708,682

4 Claims.

My present invention relates to the art of power driven striking devicesand more particularly to a portable power hammer.

My invention contemplates a portable striking unit which is so arrangedthat it may be made in a wide vanety of sizes suitable for-riveting,chipping and calking and is very nicely adapted for drilling as in rockand concrete. To facilitate this latter operation I have provided meansfor turning the drill bit so that a free cutting hole can beaccomplished without any danger of the bit being driven in and locked inplace.

The principal object of my present invention is to provide a strikingmechanism adapted to be raised against acompression spring by rotary cammeans. i

A further object of my invention is to! provide, in addition to the camand spring actuated striker, a drill turning arrangement which will movethe drill around its axis a fraction of a revolution for each blowstruck.

A further object of my present invention is to arrange for a drillrevolving mechanism which will revolve the drill between each stroke ofthe striking mechanism and will utilize the time during which there isno striker load on the drill itself. A further object of my presentinvention is to so arrange the parts of my tool that a variable strokecan be applied to the tool without any outside adjusting parts.

Other and more specific objects will be apparent from the followingdescription taken in connection with the accompanying drawing, whereinFigure 1 is a longitudinal sectional View thru a power tool made afterthe teachings of my invention. Figure 2 is a cross sectional view alongthe line of Figure 1. Figures 3 and 4 are sectional views taken alongthe line 33 of Figure 1, the same being illustrative of the mechanismemployed to impart the turning movement to the drill.

Referring to the drawing, throughout which like reference charactersindicate like parts, 6 designates generally, the striker of my tool.This consists of several associated parts, namely, the lower strikerplate 8, the upper striker plate l and a. plurality of connecting guiderods I2. Secured to the upper plate [0 is a cam follower M which in theillustration I have shown as being provided with a tapered roller l5which is adapted to engage cam it. In the present illustration I haveindicated cam l6 as a portion of a drum cam. This is very desirable whenit is used with a direct drive as illustrated. If the motor however,were set at right angles with the body of the striking mechanism itwould be necessary to employ a face cam of the more conventional type.As illustrated in Figure 2, the cam occupiesonly a portion of a circle,consequently as soon as the upper limit has been reached the fol-- lowerdrops oh? the same and allows spring :8, which has been compressed bythe rise of the cam, to throw the striker 6 down to the end of the toolthus releasing the energy stored within the spring.

To resist the twisting action of cam l6, as it lifts the follower, Iprovide a plurality of guide rods 12. These serve to secure together andspace, plates 8 and I0 andfurther as they are adapted to slide withinthe fixed guide plate 20, follower I4 is thus securely held againstrotation and consequently the entire striker assembly is moved upwardlyagainst the compression of spring I8. I have illustrated cam l6 asdriven by an electric motor 22. When such a motor is I used it should beof the high speed type, preferably mounted on anti-friction bearings asillustrated. The motor shaft extension 24, to which cam I6 is fixedlysecured, is journaled within guide plate as at 26. Each of the variousplates employed in the striking mechanism and as guide plates should beprovided with suitable relief openings as 28 to permit a freecirculation of lubricant and to prevent any air cushioning which mightdampen and absorb a large portion of the energy so that the tool wouldlose its effectiveness as a striker. Motor 22 may be provided with anysuitable switching arrangement as is illustrated at 30. However, itshould be clearly understood that an electric motor does not form anecessary part of my tool. Any source of motor power might be supplied,in fact for outdoor work, in the demolition of concrete and thelike, ahigh speed gasoline motor after the order of the outboard motors can bevery effectively substituted for the electric motor shown.

In Figures 3 and 4 I have illustrated my bit turning device. Thismechanism consists of a ratchet and pawl arrangement which are includedbetween two fixed plates 32 and 34 which are fixedly secured, as isguide plate 20, to the housing 36. Ratchet 38 is slidably engaged by thestriker bit 40 by means of the long keyway 4| and the tit key 42 formedas part of the ratchet 38. The length of keyway 4| must slightly exceedthe maximum movement of the striker 6 which in turn is controlled by theheight of the lifting surface of cam l6. Pawl 43 is adapted to engageratchet 38 and is pivoted to a fixed pivot 44. It is retained in thisoperating position by a suitable spring as 46. This pawl is merely tohold the tool bit against backward movement. The actual turning of thebit is accomplished by pawl 48, which is pivotably secure-d to the camarm 58, and has its own positionin spring 5i. Cam arm 56 is pivotablysecured to the spaced plates 32 and 3 5 on the pivot 52. It is disposedfor engagement with the sliding cam 55, which cam is in turn fixedlysecured and travels with plate 8 of the striker assembly. The extremepositions of cam E i are illustrated in Figures 3 and 4. This movementis sufficient to move ratchet 38 one tooth. A presser spring 5563 isemployed to maintain lever 55 at all times in contact with cam 5%.

A tool of this order must necessarily be designed and built particularlyfor the Work intended and this will necessitate many variations of themechanism illustrated. Striker as should preferably be provided withreplaceable tip units so that damage or injury to the tip will notnecessitate the replacement of the entire striker bit til. This has beenindicated by the coupling member Bil. It has further been founddesirable to employ a buffermeans as the spring which encircles bit itand is disposed to rest upon the fixed plates 32. Suitable packing meansshould be provided as the packing rin to prevent loss of lubricant whichmust be supplied to the striking mechanism itself to prevent ex'essivewear and heating.

The foregoing description and the accompanying drawing are believed toclearly disclose a preferred embodiment of my invention but it will beunderstood that this disclosure is merely illustrative and that suchchanges in the invention may be made as are fairly within the scope andspirit of the following claims.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

1. In a power hammer the combination with a housing, a rotary cam shaftjournaled there-in, an arcuate cam of said shaft, and operating meansfor the shaft, of a reciprocable striking assembly mounted in thehousing having a cam roller in the path of the cam, a spring for actuating the assembly, a striker mounted in the assembly, a ratchet deviceconnected to the striker, a spring pressed cam arm for actuating theratchet, and a cam arm reciprocablewith the striking assembly foractuating thepivoted cam arm.

2. In a power hammer the combination with a housing, a rotary cam shaftjournaled therein, an arcuate cam on said shaft, and operating means forthe shaft, of a reciprocating striking assembly comprising a pair ofspaced plates one of which is slidable on said shaft and a tie bolt, acam roller mounted on the slidable plate, an intermediate plate fixed inthe housing having a guide hole for the bolt, and an actuating springinterposed between the fixed plate and the other assembly plate.

3. In a power hammer, the combination with housing, having a pair ofspaced plates, a reciprocable striking assembly mounted in the housingand including a cross-plate, and a striking bit journaled in saidcross-plate and reciprccable in said spaced plates, of a ratchet wheellocated between said spaced plates and mounted on the bit, a pivotedratchet arm and a pawl pivoted thereon, and a cam arm mounted on saidcrcss-plate for co-action with the ratchet arm.

l. In a power hammer the combination with a housing, having a pair ofspaced plates, a reciprocable striking assembly mounted in the housingand including a cross-plate, and a striking bit iournaled in saidcross-plate and reciprocable in said spaced plates, of a ratchet wheellocated between the fixed plates and mounted on the bit to turntherewith and permit reciprocation of the bit, a spring pressedretaining pawl for the ratchet wheel, a spring-pressed, pivotedratchetarm, a spring pressed actuating pawl for the ratchet wheelpivoted on said arm, and a cam arm rigid with said cross-plate engagingsaid ratchet arm.

JOSEPH H. BLAKE. 1

